Officials are not expected to select the final sites until sometime this fall.

The map shows a toll plaza placed somewhere between the Interstate 380 and Scotrun interchanges or between the Delaware Water Gap exit and the Delaware River bridge.

The plan is to install cashless toll "gantries" that communicate with E-ZPass electronic toll transponders. There will be an automatic charge of $2.70 per passenger vehicle.

For drivers without E-ZPass, a high-definition video camera will photograph license plates, and a bill will be mailed the vehicle owner. There will be an extra processing fee for not using E-ZPass.

Drivers will pass through the toll plaza at highway speeds, the turnpike commission said.

Local drivers with E-ZPass, would pay nothing. Under the plan, two-axle vehicles with E-ZPass transponders would be able to pass through their first toll plaza for free, so motorists would be able to drive their first 50 or 60 miles along I-80 without being charged.

Passing back and forth through the same toll station multiple times will also be free.

Cars, SUVs, pickup trucks and school buses would get the toll discount, regardless of the state in which they are registered. Large trucks would not be eligible for it.

"The plan is to try to capture regional users of I-80," said turnpike commission spokesman Carl DeFebo. "We don't want to penalize local drivers. During meetings people made it clear I-80 is their Main Street. It is used for a lot of local movements,"

The 20 potential tolling locations are not precise. The commission simply identified stretches of highway, ranging in length from about one mile to 14 miles, where tolls could be installed.

The sites that collect the most revenue while diverting the fewest vehicles onto alternate routes will be selected, said project manager Barry Schoch.

In most cases, the traffic diversion issue will be critical, because sites close to each other are projected to produce about the same amount of money, he said.

Initially, it would cost $25 for a car to drive the full length of Pennsylvania on a tolled I-80, and $93 for a truck. In future years, tolls would rise 3 percent annually.

Drivers heading west from New Jersey already shell out a bridge toll at the New Jersey border. It is the second busiest and most lucrative toll bridge in the Delaware River Joint Toll Bridge Commission system, bringing in $25,686,882 in revenue in 2007.

If the turnpike commission puts a toll plaza at Delaware Water Gap, it is possible an agreement will be made with the bridge commission to have a joint collection point. That would prevent having two toll collections points a half mile apart.

But again, local commuters would pay nothing if they have E-ZPass transponders.

"We want to enlighten people about the importance of having E-ZPass," said DeFebo. "On the turnpike, over half of the revenue transactions are made with E-ZPass."

The estimated cost to build the toll system is $60 million. Because it would not need toll collectors, it would save hundreds of millions of dollars over the first 10 years compared to a traditional tollbooth system, the turnpike commission said.

The I-80 tolling plan received approval from the Legislature last year, but is awaiting approval from federal highway regulators.

Meanwhile, Gov. Ed Rendell is still pushing for a long-term lease of the Pennsylvania Turnpike to an international group. Rendell's lease proposal, which would cancel the need for the I-80 tolls, faces stiff opposition in the Legislature.